How can I take (simpler) measurements like what Amir does?

[McFly]

Xrk971's thread at DIYAudio will be of help also here

 

[LTig]

Thank you all, this is exactly what I was looking for! The ADC route seems promising.

Get a Motu M4 which has (so far) the best measured ADC performance below $500. The best one would be the RME ADI-2 PRO fs but that is expensive - OTOH it's more than 10 times cheaper than @amirm's AP.

I am a big fan of used gear, and have had much success on Craigslist. If I am looking at digital scopes, what is/are the key things I should look for to determine suitability?

12 or 14 bit ADC resolution. Most affordable DSOs have only 8 bits, and I don't think you get 16 bit for cheap money, even used (if it exists at all). Owon makes DSOs with 12 and 14 bit ADC resolution (XDS2102A 12 bit, XDS3064AE 14 bit) but I have no clue if they are any good or reliable.

 

[tune]

Will the combination of E1DA Cosmos ADC (ES9822 PRO) and APX500 FLEX work well?

 

[Lambda]

Get a good fast ADC like the motu m4 and do it in software.
Like https://www.baudline.com/

REW room acoustics and audio device measurement and analysis software

REW is free software for room acoustic measurement, loudspeaker measurement and audio device measurement and analysis

www.roomeqwizard.com